Brain incorporation of 11C-arachidonic acid, blood volume, and blood flow in healthy aging: a study with partial-volume correction.
Brain incorporation of 11C-arachidonic acid, blood volume, and blood flow in healthy aging: a study with partial-volume correction.
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发表时间：
2004-09
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通讯作者：
G. Giovacchini;A. Lerner;M. Toczek;C. Fraser;Kaizong Ma;J. Demar;P. Herscovitch;W. Eckelman;S. Rapoport;R. Carson
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作者：
G. Giovacchini;A. Lerner;M. Toczek;C. Fraser;Kaizong Ma;J. Demar;P. Herscovitch;W. Eckelman;S. Rapoport;R. Carson
具有11 C-花生四烯酸（AA）的未标记PET可用于量化与磷脂酶A2（PLA 2）相关的神经信号传导。动物研究表明，随着年龄的增长，这种信号系统的活性降低。本研究的目的是评估健康老龄化对部分容积校正（PVC）前后11 C-AA脑掺入的影响。方法对8例青年和7例老年健康受试者（平均年龄± SD，27 ± 5岁和65 ± 9岁）进行15 O-水快速团注脑血流量（CBF）的绝对测量。注射11 C-AA后约15 min，进行动态60 min三维扫描。校正11 C-AA放射性帧的头部运动，并配准到磁共振（MR）图像。将3段（3S）和2段（2S）PVC逐像素应用于活动帧。对于3S方法，通过外推白色物质隶属度> 0.99的像素的活性值，使用新的自动方法估计白色物质值。生成11 C-AA脑掺入率（K*）和脑血容量（Vb）以及CBF的参数图像，并获得区域灰质值。结果在皮层区中，年轻人和老年人在PVC前后K* 和Vb绝对值无显著性差异（未校正P < 0.05）。老年组额叶皮质CBF明显降低。归一化后的全球灰色平均值，K*，Vb，和CBF值显示显着减少，在额叶的老年受试者，这些差异均不显着PVC后。结论这些结果证实了以前的PET研究结果，即健康老龄化对静息脑功能的影响最小。正确的PVC方法在PET生理指标的准确定量评估中至关重要。
UNLABELLED PET with 11C-arachidonic acid (AA) can be used to quantify neural signaling related to phospholipase A2 (PLA2). Animal studies suggest reduction in the activity of this signaling system with age. The aim of this study was to evaluate the effect of healthy aging on brain incorporation of 11C-AA, before and after partial-volume correction (PVC). METHODS Absolute measurements of cerebral blood flow (CBF) were obtained in 8 young and 7 old healthy subjects (mean age +/- SD, 27 +/- 5 y and 65 +/- 9 y) with bolus injection of 15O-water. About 15 min later, dynamic 60-min 3-dimensional scans were acquired after the injection of 11C-AA. Radioactivity frames of 11C-AA were corrected for head motion and registered to magnetic resonance (MR) images. A 3-segment (3S) and a 2-segment (2S) PVC was applied pixel-by-pixel to the activity frames. For the 3S method, the white matter value was estimated using a new automatic method by extrapolating the activity values of pixels with white matter membership > 0.99. Parametric images of the brain incorporation rate of 11C-AA (K*) and cerebral blood volume (Vb), as well as CBF, were generated and regional gray matter values were obtained. RESULTS Among cortical areas, there were no significant differences (uncorrected P < 0.05) in K* or Vb absolute values between young and old subjects before or after PVC. A significant reduction of CBF was detected in the frontal cortex of the elderly group. After normalization to the global gray average, K*, Vb, and CBF values revealed significant reductions in the frontal lobe of old subjects; none of these differences were significant after PVC. CONCLUSION These results confirm previous PET findings that brain function at rest is minimally affected by healthy aging. Proper PVC methodology is of critical importance in accurate quantitative assessment of PET physiologic measures.